The present invention relates to a projector which processes light emitted from a light source by an optical element to project a processed projection optical image onto a screen by a projection lens.
Heretofore, this type of projector, for example, a liquid crystal projector has a constitution in which a light source, a liquid crystal panel (an optical element), a projection lens and the like are mounted in a main body. The liquid crystal panel is constituted of three liquid crystal panels for processing (modulating) color rays in accordance with image information generally as light bulbs. Moreover, light emitted from the light source is split into the color rays, processed (modulated) by the liquid crystal panels in accordance with the image information and synthesized as a projection optical image through a prism and the like. Then, the synthesized projection optical image is enlarged and projected onto a screen by the projection lens.
In such a projector, the light source and the optical element (the liquid crystal panels, etc.) are heat generation sources to bring the inside of the main body into a heated state. Therefore, a plurality of fans are installed in the main body, and supply (blow) air outside the projector (the outside air) to the optical element and the light source to release the heat. In this case, the light source has a very high temperature of about +900° C., and the heat can sufficiently be released by the outside air, but the upper limit of the use temperature of the optical element is a comparatively low temperature. When, for example, the liquid crystal panels are used as the optical elements, the upper limit of the use temperature is about +70° C. to +80° C. Therefore, the amount of the heat to be released from the optical elements is noticeably influenced by an outside air temperature. That is, when the outside air temperature is low, the optical elements can sufficiently release the heat to the supplied outside air. However, when the outside air temperature is high, the amount of the air to be blown by the fans needs to be increased to secure the amount of the heat to be released. Therefore, noise due to the operation of the fans increases, and a problem also occurs that power consumption remarkably soars.
Moreover, the outside air receiving the heat is released to the outside, but this released outside air is again sucked by the fans and supplied to the projector. There also occurs a problem that a so-called short cycle of the air after the heat release is generated, and any excellent heat release effect cannot be obtained.
To solve such a problem, it has been suggested that low-temperature air be produced by thermoelectric cooling, to cool the liquid crystal panels (the optical elements) (e.g., see Japanese Patent Application Laid-Open No. 2005-121250).
The problem of the noise can be solved by such thermoelectric cooling, but such thermoelectric cooling has a poor energy efficiency, and a heat generating section for the thermoelectric cooling is integrally constituted. Therefore, means for releasing the heat to the outside air (a heat sink or the fans) is required near a cooling target, and a problem has occurred that a spatial restriction is generated to remarkably lower a degree of freedom in design.